The work proposed deals with embryonic development and differentiation in the common snapping turtle, chelydra serpentina. The current objectives are as follows: 1. Analysis of temperature sensitive periods during incubation for sex determination. 2. Production of intersexes and study of their causes and morphology. 3. Incidences of sex in eggs hatched in outdoor nests and relation of nest temperatures to sex-ratio. 4. Facilitation of work by other investigators on problems involving development of the turtle.